An analytical method for developing a theoretical load-settlement curve for axially loaded piles in clay is presented. The method is based on the correlation of the ratio of load transfer to soil shear strength as a function of pile movement. The results of studies of field tests of instrumented piles and laboratory tests of small piles in clay are used to obtain the desired correlation. The correlation is presented in the form of a family of curves that are obtained when the ratios of load transfer to soil shear strength versus pile movement are plotted as a function of depth. The validity of the family of correlation curves is checked by comparing computed and actual load-settlement curves for some typical field tests. Results obtained by this method indicate that the method may be used effectively to determine load-carrying capacity for axially loaded piles in clay.

Closure to “Load Transfer for Axially Loaded Piles in Clay”

A method of calculation is presented which makes it possible to determine the stress, strain, and pore pressure distribution resulting from the expansion of a spherical or a cylindrical cavity in an infinite medium. It is assumed that the medium consists of a saturated clay and that the expansion occurs in undrained conditions. The calculation is based directly on the stress-strain curves of the clay obtained by conventional consolidated-undrained triaxial tests. The numerical calculations show that for a given type of cavity the shape of the total and effective stress-distribution curves is considerably influenced by the value of overconsolidation ratio. The method has been tentatively applied for calculating the bearing capacity factor N c for deep foundations and the excess pore pressure set up during driving of piles in a saturated clay.

Closure of "Expansion of a Cavity in a Saturated Clay Medium"

This paper aims at analyzing the active and passive lateral earth pressures exerted on retaining walls due to the anisotropic medium of dry and noncohesive backfill subjected to the modifi...

Limit Analysis of Modified Pseudodynamic Lateral Earth Pressure in Anisotropic Frictional Medium Using Finite-Element and Second-Order Cone Programming

An elastoplastic solution to undrained expansion of a cylindrical cavity in SANICLAY under plane stress condition

Three-dimensional tunnel face extrusion and reinforcement effects of underground excavations in deep rock masses

This paper presents a generic analytical solution for stresses and displacements developed around an arbitrarily shaped underground opening excavated in an elastic soil/rock mass with biaxial in situ stresses. A series of separable functions satisfying the governing biharmonic equation is employed as the basic stress function for the problem considered. With the basic stress function and the stress rotation equation, the normal stress and the shear stress on the opening boundary surface are expressed in terms of separable function series with unknown coefficients to make use of the boundary condition. Based on the variational theory, the unknown coefficients are determined by minimizing the difference between the real stress boundary condition and the assumed stress function on the opening surface. The excavation responses around different shapes of openings, including elliptical-shaped, ovaloid-shaped, horseshoe-shaped, and D-shaped openings, are investigated and compared with those from the finite-element simulations. The results show that both the stress field and the displacement field agree well with those from the corresponding numerical model, which verify the proposed solving technique. The proposed solution provides an easy, generic, and feasible approach to assess the stresses and displacements developed around an arbitrarily shaped opening, which is simpler and more straightforward than the complex theory–based solutions. 

A Generic Analytical Elastic Solution for Excavation Responses of an Arbitrarily Shaped Deep Opening under Biaxial In Situ Stresses

Stress transform method to undrained and drained expansion of a cylindrical cavity in anisotropic modified cam-clay soils

This paper presents a new analytical solution for deep circular tunnels in rock with consideration of disturbed zone, 3D strength and large strain. The rock is assumed to be elastic–brittle–plastic and governed by a 3D Hoek–Brown yield criterion. To take the large displacement around a tunnel into account, the large-strain theory is adopted to determine the displacement of rock in the plastic zone. Based on the equilibrium equation, constitutive law and large-strain theory, the governing equations for the stresses and radial displacement around the tunnel were derived and solved by using MATLAB. The proposed solution was validated by using it to analyze a tunnel and comparing the results with those from numerical analysis using a finite difference code. Finally, extensive parametric studies were performed on tunnels in both poor-quality and good-quality rock masses with respect to stresses and radial displacement. The results indicate that the disturbed zone and the flow rule both have significant effects on the stress and displacement distributions around the tunnel.

Analytical Solution for Deep Circular Tunnels in Rock with Consideration of Disturbed zone, 3D Strength and Large Strain

This paper investigates a basement excavation adjacent to running metro tunnels and underground pipelines in Shanghai soft soil The zoned excavation technique was adopted to control the de

Haohua Chen

Papers

An elastoplastic solution to undrained expansion of a cylindrical cavity in SANICLAY under plane stress condition

A Generic Analytical Elastic Solution for Excavation Responses of an Arbitrarily Shaped Deep Opening under Biaxial In Situ Stresses

Stress transform method to undrained and drained expansion of a cylindrical cavity in anisotropic modified cam-clay soils

Analytical Solution for Deep Circular Tunnels in Rock with Consideration of Disturbed zone, 3D Strength and Large Strain

Performance of a zoned excavation by bottom-up technique in Shanghai soft soils.